Carburetor



Sept. 7, 1943.

G. M. BICKNELL CARBURETOR Filed May 7, 1940 4 Sheets-Sheet 1 INVENTOR GEORGE M. BICKNELL M46 4 (LN ATTORNEY Sept. 7, 1943. cs. M. BICKNELL CARBURETOR Filed May '7, 1940 4 Sheets-Sheet 2 M Q: A

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INVENTOR GEORGE M. BICKNELL ATTORNEY Sept. 7, 1943. a. M.BICKNELL CA'RBURETOR Funding 7, 1940 4 Sheets-Spam. 4

XR Q 3k f INVENTOR GEORGE M. BICKNELL ATTORNEY u Patented Sept. 7, 1943 CARBURETOR George M. Bieknell, St. Louis,

Carter Carburetor Corporation, a corporation of Delaware Mo., assignor to St. Louis, Mo.,

Application May 7, 1940; Serial No. 333,759

2 Claims.

This inventionrelates to carburetors for in-.

It is a further object of the present invention to provide a carburetor of the above-character having a novel and improved semiautomatic fuel metering device.

It is a further object of the present invention to provide a carburetor of the above. character having a novel and improved accelerating device.

Further objects and advantages of the present invention will be hereinafter set forth in the following specification and accompanying, drawings .in which like numerals indicate identical parts.

Fig. 1 is a plan view, partly in section, of a carburetor constructed in accordance-with the present invention. V

Fig. 2 is an elevation of the carburetor shown in Fig. 1 as viewed on line 22 of Fig. 1.

Fig. 3 is a vertical section of the carburetor in Fig. 1 taken on line 3-3 of Fig. 1.

Fig. 4 is a horizontal section taken on line 4-4 of Fig, 2.

Fig. 5 is a vertical section taken on line 5-4 of Fig. 1.

FlFig. 6 is a vertical section taken on line 6-6 of Fig. '7 is a fragmentary section taken on line I of Fig. 1.

Fig. 8 is a detailed view of the metering rod and attaching screw.

Fig. 9 is still another side elevation being par tially sectionalized in order to show the idling system,

In the drawings, numeral I indicates a main carburetor body casting having a suitable flange 2 formed at the lower end thereof for attaching a carburetor to the intake manifold of an internal combustion engine. A mixing conduit 3 is formed in the main body casting and an adjacent constant, level fuel chamber 4 is cast integral therewith. A portion of the mixing conduit 3 has a. Venturi-forrn as indicated at 3a which converges to the constriction or throat 5. The upper end of body casting l is provided with a smoothflange surface to which is attached an air inlet casting or air horn 6 and a fuel bowl cover I by means I of attaching screws 8. Depending from the air horn casting 6 and projecting into the upper end of the mixing conduit are two concentric Venturi tubes 9 and I0. Venturi tube 9 being arranged to discharge near the throat of venturi HI and venturi Hi being arranged to discharge near the constriction 5.

The outlet ll of the mixing conduit is controlled by a plate-type throttle valve [2 which is rigidly attached to a throttle shaft l3 by means of screws l4. Throttle shaft I3 is journalled in the bosses I5 and l5a. For operation of the throttle valve a stamped throttle operating lever l5 rigidly attached to one end of the throttle shaft I3 is provided. The throttle lever [B is fabricated from sheet stock by stamping and forming and is provided at one end with a perforation I! to receive a remote control rod (not shown). The throttle lever is normally urged toward a throttle closing position by the usual throttle pull back spring (not shown) which generally forms a part of the remote control linkage. Lever I6 is also provided with a pair of parallel bent up portions l8 and 19 (Fig. 4), which are perforated and internally screw threaded to receive a throttle lever adjusting screw 20, Provision of adjusting screw 20 permits a fine adjustment of the throttle valve when in a near closed or idling position. An upper wing lug 21 on body casting l provides a throttle closing limit abutment and a lower wing lug 2la provides a/throttle opening limit abutment. A narrow tang 22 formed as part of lever 16 abuts lug 2la as the throttle valve reaches its open limit. Lever I6 is further provided with a notched circular perforation 23 which receives a connector link 24.

The air inlet passage 25 is controlled by a plate-type choke valve 26 which is eccentrically mounted for rotation with the choker shaft 21 which, in turn, is journalled in the bosses 28 and 29. A pair of abutments 2501. within the air inlet passageway and cast as an integral part of the air horn casting 6 provide a wide open stop for the choke valve. Referring to Fig. 3 the left end of choker shaft 21 projects into a casing 30 which is cast as an integral part of the air horn casting 6. The casing 30, together with the cupshaped cover 31 form a housing which completely encloses mechanism for the automatic control of the choker valve 26.

Cast as an integral part of the fuel bowl cover I is a combination fuel inlet and vent boss 82, see Figs. 1, 6 and 9. Boss 82 is provided with a comparatively large, horizontal bore 83 in which is retained a cylindrically formed wire screen strainer 84 by a screw engaged combination retainer plug and fuel inlet fitting 85. The plug 85 is provided with a through bore 86 one end of which is .counterbored as indicated at B1 and receives the cylindrical strainer 84 by press-fitting. This arrangement facilitates convenient removal of the strainer for cleaning. The other end of bore 86 is screw threaded as indicated at -88 to provide suitable attachment for a fuel conend of idling tube dle valve 95 in a well known manner to maintain a constant level of fuel in chamber 4 substantially as indicated by the line a:-:c. Fuel is sup plied to the carburetor mixing conduit for normal and full speedand load operation of the engine through a metering jet 96, through passages 91 and 98 and is discharged through nozzle 99 into the primary Venturi tube 9, see Figs. 3 and 4. Fuel for low speeds or idling operation is also metered by jet 96 and passes into passage 9'! from whence it passes through the idling jet tube I through passages i0! and H32 and is discharged into the mixing conduit near the edge of throttle valve l2 through a port 5920,, see Figs. and 9. The idling supply system further includes the metering restriction I03 at the lower Hill, the air bleeds i114 and 5% which communicate with the mixing conduit, the economizing restriction I06 located therebetween in "passage Hll, and the auxiliary discharge port I07 controlled by the'idle adjustment screw M8. The adjustable port it? provides a means for varying the volume of the mixture supplied by the idling system.

The amount of fuel available for aspiration from the main nozzle 99 and idling ports iillfia and I0! is varied in accordance with engine intake manifold vacuum and throttle position by positioning a stepped and/or tapered metering rod l09'axia1ly in metering jet 9%. As the me= tering rod 569, Fig. 5, is moved toward the left the net opening of jet 95 is decreased. To posi= tion the rod i 09 in accordance with manifold vac== uum, a flexible diaphragm member Hi! being rigidly attached to rod H19 at its center by means of the plunger member H I is provided. Referring to Fig. 5 the left hand side of diaphragm H0 is subjected to intake manifold suction by reason of passages H2, H3, lid and H5 which open as a port lit in the wall of the mixing con= duit below the throttle valve. The recess ill in the carburetor body casting and the generally cup-shaped cover plate H3 form a working chamber for the diaphragm. The recess ii'l communicates with the fuel chamber 4 through a passage 117a, see Figure The cover plate i 18 firmly clamps the periphery of the diaphragm and is attached to the body casting by means or screws i9., The central perforation of cover plate H8, wherein is fitted for reciprocation the plunger HI, is provided with a packing gland i203. The plunger iii passes through a central perforation in diaphragm 5 ill and is firmly attached thereto by riveting or spinning over the: reduced end of the plunger as indicated at till.

Plunger ii i is further provided with a through axial bore of suificient size to permit the passing of the entire metering rod and which is provided with screw threads 52% at its outer end. The metering rod is fitted at its outer end with a partially hollow screw plug H112 to which it is assern-= bled by insertion and staking as indicated at E23, Fig. 8. It will be seen from the foregoing that the metering rod )9 may be removed or assem= bled without the necessity of removing the cover plate H8 and diaphragm H0. Metering rod its is normally urged to the right, Fig. 5, by the lever aeaaeoe 24 which is acted upon by a spring I25. The lever 526 is carried on pivot H26 which also forms a pivot for a second lever I21 yvhich is, in turn, connected to a lever E28 by means of a link I29.

Lever H8 is rigidly attached to the throttle shaft i3.

Relative motion of levers I24 and i 21 is prevented in one direction by the finger i3! carried by lever 52 3. It will be understood that spring use is so proportioned and calibrated with relation to the effective area of diaphragm me that the desired position of the metering rod for a. given manifold vacuum is attained. From the foregoing it will be seen that sumcient vacuum applied to the left side of diaphragm lit will move metering rod 509 to the left; that normally the metering rod is urged to the right by spring 625 and that a clockwise rotation of the throttle shaft 63 (which is a throttle opening movement) will forcibly move the metering rod to the right in a less restricting position in jet 96.

It will also be noted that a movement to the right of diaphragm Mil caused by a drop in manifold vacuum or throttle opening movement will displace the fuel in chamber ill causing an increased pressure on jet 96 and also momentarily raising the fuel level in the constant level chamher. This enriching effect is highly desirable.

Fuel for acceleration is supplied to the mixing conduit under pressure by the diaphragm type accelerating device generally indicated at 5322, Figs. 2, 5, and 6, and which comprises a c r chamber 533 formed by a recess in casting and by the recessed cover E30 which is attached thereto by means of attaching screws i355. A flexible diaphragm member 3 36 firmly clamped at its periphery between cover I34 and the carburetor body is provided and forms a partition in chamber 1! The diaphragm H6 is attached at its center to a horizontal plunger 837 which passes through the cover 1134 and projects therefrom. A spring E38 bearing at one end against retainer 639 and at its other end against cover normally urge the diaphragm E36 and plunger 53? toward the right, Fig. 5, which is an intake stroke. A rocker arm M0 pivoted at one end Mi and having attached at its other end at l a spring M2 which is connected to lever i223 moves the plunger and diaphragm to the left (discharge stroke) as the lever H8 is rotated clockwise (throttle opening direction).

It will be understood that spring M32 is substantially stronger than spring 538 and that its provision in lieu of a non-yielding link results in a smooth yielding pressure being exerted upon the plunger and diaphragm $38 which is desirable.

The accelerating device further comprises inlet passageways Hill and 1152, Figs. 4 and 5, leading from the constant level fuel chamber a to the expansible chamber 333. A cylindrically formed wire mesh trainer 653 is provided and is retained in passage I52 by the screw threaded inlet check plug The inlet check plug H56 is provided with a valve seat E55, a disc check valve E56 and a valve retainer E57. The fuel is discharged from chamber i351? through passages I58, H59, diagonal passage Mid and accelerating jet ifil into the mixing conduit, see Figs. 5 and 7. A discharge valve seat is formed at the lower end of passage I159 at 562 by a reduction in diameter and a gravity seating ball check valve N53 is provided and adapted to engage seat 52. The upper end of passage E59 i screw threaded and the main fuel passage 98 to'a receives a screw plug I04 which is provided with a downwardly extending stem I65 which limits the upward movement of ball check I83 when the same is acted on by discharge pressure. Referring to Fig. 7 the accelerating jet IOI is provided with a plurality of transverse holes I66 which provide communication between the longitudinal jet passage I61 and the atmospheric vent I68. This provision is made to preclude aspiration of fuel through jet I6I.

A decided advantage gained by the present arrangement of the accelerating device is that, by extending the discharge passageway upwardly from the very top of the expansible chamber I33 to a point above the fuel level, pressures which frequently build up in chamber I33 due to vaporization are released without the forcing of fuel from the chamber as occurs in many constructions. This advantage has particular significance due to the importance of maintaining a full charge of fuel in the accelerating chamber.

Referring to Fig. 3, a tical passageway I69 is comparatively large verprovided, extending from point above the upper part of this passagev comthe mixing conduit through a provision has the purpose of refuel level. The municates with tube I10. This lieving vapor. pressures at the base of nozzle 99 and its operation is fully described in my copending application, S. N. 255,674, filed February 1 0, 1939, now Patent No. 2,234,946.

" The operation of the carburetor is as follows:

Fuel is supplied to the float chamberd through inlet passage 86, screen 84, and'passages B9, 90 and 92 wherein a substantially constant level as indicated by line :v-a is maintained by the action of the float 93 on needle valve 95.

Fuel for normal andhigh speed operation is supplied to the mixing conduit from fuel chamber 4 through metering jet 96, passages 91, 98 and nozzle 99. During comparatively light load operation the intakemanifold suctionwill act on diaphragm IIO to move metering rod I09 toward the left, Fig. 5, that'is toward a more restricting position. The position of the metering rod under these conditions will also be determined by the throttle position. When sufflcient load is applied to the engine-for any given throttle position to cause a sufficient resulting drop in manifold vacuum, spring I25 will urge the metering rod toward the right to a less restricting position.

Fuel for idling operation is supplied. to the mixing conduit from fuel chamber 4 through jet 90, passage 91, idling jet I03, idling tube I00, passages IOI and I02 and is discharged into the mixing conduit near the upward opening edge of throttle valve I2 through ports I020. and I].

Fuel for acceleration is supplied under pressure to the mixing conduit from the accelerat-.

ing chamber I33 during the discharge stroke of diaphragm I36, through passages I58, I59, I60 and discharge jet IBI. The diaphragm I36 is actuated through its discharge stroke by an opening movement of the throttle valve by means of linkage comprising the rocker arm I40, the spring I42, and lever I28.

When the throttle is suddenly opened from nearly closed position, pressure in the carburetor outlet and in diaphragm control passages H2 and H3 increases, causing rapid inward movestant level chamber, an accelerating discharge ment of diaphragm IIO by spring I25. This forces liquid fuel back through open bowl communication IIIa. momentarily raising the level in the bowl, and through main metering jet 96. Additional fuel is thus supplied to the mixture conduit through the main nozzle both because of the raised level and consequent increased pressure in the bowl and because of the extra charge of fuel forced directly int-o the main nozzle passage. As the throttle is opened, the distance diaphragm I I0 can move because of a drop in suction in the carburetor becomes progressively less, since the diaphragm is impelled inwardly by lever I24 operated by the throttle. This is an advantage because less auxiliary pick up fuel is needed for acceleration from a substantially open throttle position than from a nearly closed throttle position.

The invention is not limited in details to the structure shown but may be modified in various respects as will occur to those skilled in the art and the exclusive use of all such modifications that come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, means forming a mixing conduit, a throttle valve controlling the outlet of said mixing conduit, a constant level fuel chamber, a fuel inlet, a float valve controlling said inlet, a main 'fuel nozzle, a throttle actuated accelerating device constructed and arranged to discharge fuel into said mixing conduit upon opening movements of said throttle valve a spring-opposed, suction responsive device for momentarily raising the level of fuel in said constant level chamber upon reduction of the actuating suction, said suction responsive device being subjected on opposite sides to the suction in said mixing conduit posterior to said throttle valve and to the fuel in said chamber, and mechanism coacting with said throttle valve and said device to progressively reduce the fuel level raising effect of said suction device, due to a drop in suction, as said throttle valve is moved towards an open position.

2. In a carburetor, meansforming a mixing conduit, a throttle valve for controlling the outlet of said mixing conduit, a constant level fuel chamber, an inlet port for said fuel chamber, a float controlled valve for said inlet port, an accelerating device receiving fuel from said conpassage leading from said accelerating device to said mixing conduit, said. accelerating device being constructed and arranged to discharge fuel into said mixing conduit upon opening move ments of said throttle valve, a main fuel passage leading from said constant level chamber to said mixing conduit, a spring-opposed, suction responsive device forming an expansible chamber in communication with said main fuel passage and acting to raise the fuel level in the fuel chamber to thereby increase the discharge of fuel through said main fuel passage upon a reduction in suction in said mixing conduit posterior to said throttle, and mechanism coacting with said throttle valve and the device acting to progressively reduce the effect of said device, due to drop in suction, as said throttle valve is moved toward an open position.

GEORGE M. BICKNELL. 

